Adaptive Observer-Based Disturbance Rejection Predictive Rotational Speed Control for Hydraulic Rock Bolters

Aiming at nonlinearity, time-varying parameters, variable surrounding rock conditions and complex external disturbances of the rotary system of hydraulic rock bolters in underground coal mines, traditional control methods suffer from low rotational speed tracking accuracy, weak anti-disturbance capacity, frequent sticking and drill bit damage. This paper investigates high-precision adaptive rotational speed control for rock bolters. First, a drill bit optimal rotational speed calculation model is established by integrating the rock hardness coefficient and drill bit wear characteristics with a wear correction coefficient. Considering the nonlinear friction of the rotary system and the dead-zone nonlinearity of the electro-hydraulic proportional valves, a valve-controlled motor rotary system model with nonlinear compensation is constructed. A smooth adaptive nonlinear function is designed, and a reduced-order adaptive nonlinear observer is built to accurately estimate unmodeled system states and lumped disturbances. A composite disturbance rejection predictive control strategy based on the adaptive observer is proposed. The simulation results show that the proposed adaptive observer achieves significantly improved disturbance observation accuracy and stability compared with conventional observers. The comparative simulations verify that the composite control strategy realizes fast and accurate tracking of the rotational speed of the rock bolters. This research provides the theoretical support for the adaptive high-precision rotational speed control of hydraulic rock bolters under complex working conditions, delivers critical engineering value for improving the efficiency and safety of roadway support construction, and promotes the intelligent upgrading of underground support equipment.